Steel making material recycling system

ABSTRACT

A steel processing material comprises a dried post combustion material (PCM) and a slag foaming material.

TECHNICAL FIELD

The present invention relates to steel processing material, methods ofpreparing such materials and methods of manufacturing steel using suchmaterials. The materials and methods of the invention allow the use ofiron-bearing by-product material in the steel industry.

BACKGROUND OF THE INVENTION

In the steel industry, especially when melting scrap steel in anelectric arc furnace, solid waste material, commonly referred to asFurnace Exhaust Material (FEM), from the post combustion exhaust chamberis generated. Typically, an exhaust system is used to direct thismaterial to a bag house. The FEM typically is very high in iron (Fe)content. Some of this material, called post combustion material (PCM),comprises particles that are too heavy or too large to be exhausted tothe bag house. Such material can be gravity fed from the combustionchamber to a drop out box or similar arrangement. Thus, FEM is generatedfrom the post combustion chamber drop out box as PCM or is evacuated onto the bag house as bag house dust. The iron content from eitherlocation is typically about 40% by weight. However, the iron content canvary from about 20% to about 75% by weight. These materials can alsohave about 15-25% by weight moisture, about 20% by weight of materialsimilar in content to the slag foaming material currently added to thefurnace, and up to about 5% by weight of other metals and oxides. Theslag foaming material can include calcium and magnesium oxides, iron,carbon and/or manganese.

The slag foaming materials are originally introduced into the steelmaking process to develop a foamy slag that, among other things, createsa chemical environment in a heat of steel where the exchange of oxygenand other unwanted materials in the steel can occur. However, due to theextreme temperatures, various chemical reactions, and the necessaryenvironmental exhausting of furnace gases, some of the slag foamingmaterials are undesirably exhausted into the flume or exhaust chamber.Similarly, some of the iron in the steel and in the slag can also beexhausted into the chamber. These materials typically agglomerate orotherwise combine to create dust or larger particles within the exhaustchamber.

The combustion chamber or the post combustion chamber duct work of asteel manufacturing assemblies offer water cooled. Water from leaks,sprays or any other source may travel by gravity through the postcombustion chamber and wet the post combustion material. Post combustionmaterial removed from the drop out box is typically stored in an outsideyard for further disposition. Either in the drop out box or in the yard,the PCM can absorb a great deal of moisture from the atmosphere, rain orother sources. The moisture content of wet PCM is usually significantlyabove 2% and usually is greater than 6% and, more typically, is about15-20%, all by weight. However, some processes may avoid the moisturepickup thus delivering a dry PCM, confirming less than about 2% byweight.

Currently, PCM undergoes an expensive secondary reclamation processes torecover the heavy metals or is sent to landfills for disposal.

The use of secondary reclamation processes to recover the heavy metalsare generally very expensive. Currently such processes require expensiveequipment, extensive handling of the material, and the use of chemicaladditives. After processing, the material may still not be desirable inmany applications. U.S. Pat. No. 5,738,694, to Ford, dislcoses anexample of the secondary processing of similar material. Ford disclosesiron rich material waste products, such as electric arc furnace dust,formed with an organic binder into discrete shapes, such as briquettesand/or other solid shapes. The shapes can then be used in iron and steelmaking processes and may allow recovery of the iron and heavy metalsvalues in the waste product.

Some manufacturers have found it more economical to send the PCM tolandfills. The cost of reclaiming the heavy metals can be much greaterthan the cost of landfilling and the decrease in steel quality and lifeof the furnace is too great to justify merely reintroducing the PCM backinto the process.

Other iron-bearing waste materials may be generated throughout the steelmaking process. As previously discussed, bag house dust is continuallymade in the steel making process. Steel makers continue to struggle withcost effective means of processing, selling or otherwise eliminating baghouse dust. The secondary processes in steel making also create asignificant amount of iron-bearing waste materials, including forexample, scale generated at the caster or rolling mill. Other sources ofiron wastes include iron fines generated by the recovery of rollingsolution in a cold rolling mill, the cleaning of steel in a galvanizingline or other cleaning/finishing processes. A further source of ironwaste is a high purity iron oxide recovered from spent pickle liquor ofa pickling process. All of these sources of by-product iron materialscreate a dilemma for the steel maker in dealing with disposal of thesematerials.

SUMMARY OF THE INVENTION

In one embodiment, the invention relates to steel processing materials.The steel processing materials comprise a dried post combustion material(PCM) and a slag foaming material.

In another embodiment, the invention is directed to a method ofpreparing the steel processing material. The methods comprise recoveringPCM from a steel making process and drying the PCM. In a furtherembodiment, the methods of preparing the steel processing materialcomprise recovering dry PCM from a steel making process and mixing thePCM with a slag foaming material.

In another embodiment, the invention is directed to methods ofmanufacturing steel. The methods comprise melting a first heat of steel,whereon the heat has a liquid steel portion and a foamy slag portion.The melting generates PCM. The PCM is dried and added into a second heatof steel.

In yet another embodiment of the current invention a steel processingmaterial comprises a recycled material and a slag foaming material.

Advantages and novel features of the present invention will becomefurther apparent to those skilled in the art from the following detaileddescription, which simply illustrates various modes and examplescontemplated for carrying out the invention. As can be realized, theinvention is capable of other different aspects, all without departingfrom the invention. Accordingly, the drawings and descriptions areillustrative in nature and not restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming the present invention, it is believed that thesame can be better understood from the following description, taken inconjunction with the accompanying drawing, in which:

FIG. 1 illustrates a schematic view of an exemplary embodiment of a PCMreclamation facility in accordance with the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Reference can now be made in detail to various exemplary embodiments ofthe invention, some of which are also illustrated in the accompanyingdrawing. Throughout the specification and claims, all ports andpercentages are by weight unless otherwise specified.

Solid waste material such as Furnace Exhaust Material (FEM) is generatedby the steel making process. The current invention contemplates removingsome of the moisture content and/or otherwise recycling FEM materialback into the process. The FEM is typically generated as particlescollected from the drop out box, known as Post Combustion Material(PCM), or dust from the bag house, as described above. Different plantsor operations in the steel industry may use different terms other thandrop out box particles or bag house dust, however, the term “postcombustion material” as used in this invention should be understood tocover any iron-bearing material from the exhaust of a steel makingfurnace. Such furnaces may include a basic oxygen furnace, an electricarc furnace, a degasser, or any similar furnace creating solid materialfrom the exhaust chamber. The post combustion material as used in thecurrent invention further includes iron-bearing solid waste materialssuch as iron fines, scale, iron oxide from pickle liquor, or othersimilar steel making materials as known to those skilled in the art.

If PCM is directly reintroduced back into the steel making process,several problems can occur, for example, because the moisture is brokendown into its elemental components (H₂ and O₂). Excess hydrogen in thesteel can decrease the castability and increase porosity of the steel.The increased oxygen both increases melting time, requiring more energyfor heat, and produces “dirty” steel. Reactions from both the hydrogenand oxygen can also be detrimental to the life of the furnace.Additional processing costs may also be incurred, for example, byincreased cost and time at a treatment facility such as a ladle furnace.Further, the moisture alone can cause safety concerns if the PCM issubmerged in liquid steel because the expansion of the moisture, fromwater to steam, can cause an explosion.

Reintroducing the PCM back into the process may also cause the foamyslag characteristics of the furnace to be changed because the moistureof the PCM decreases the effectiveness of the foamy slag. The chemicalreactions between the steel and slag may be decreased and poor coverageof the steel by the foamy slag may occur. Nitrogen pickup may alsoincrease as poor coverage of the foamy slag allows air to contact theliquid steel.

In one embodiment of the current invention, wet PCM, typically at about15 to 25% by weight water content, is obtained from the steel makingfurnace, for example in particle form from a drop out box. The wet PCMis dried to remove at least a portion of the moisture. For example, inone embodiment, the PCM is air dried to about 6-15% by weight watercontent. The PCM can be sorted to facilitate further drying, otherprocessing, or subsequent use of the material. In one embodiment thesorting is accomplished by screening to obtain one or more fractions ofdesired average particle size. In a further embodiment, the PCM issorted to obtain a fraction having a maximum particle size, for exampleof about 1 inch, more specifically of about ¾ inch, even morespecifically of about 5/16 inch. The sorted material can then besubjected to further processing, and in one embodiment is dried furtherto about 2% by weight water content. The PCM, now referred to as driedPCM, can be reintroduced into the steel making process. For example, thedried PCM can be added by charging buckets, direct charging, orotherwise reintroduced into the steel making process using techniquesknown to those skilled in the art.

The further drying may be achieved using any apparatus or method knownin the art. For example, the drying may be conducted using a rotarydryer, common in the steel industry, or using a screw auger dryer. Thescrew auger dryer can heat the PCM by, for example, induction heaters,gas-fired heaters or other such heating systems. Use of a screw augerdryer can be beneficial in that an auger is relatively inexpensive ascompared with a rotary dryer, the screw auger dryer can be installed ina relatively small space, and installation time for a screw auger dryercan be a few weeks compared to several months for a rotary dryer. Ascrew auger with an induction drier or other type of electric operateddrier may also be more environmentally friendly as compared with arotary drier such as one requiring natural gas or fuel oil or one havinga fluid bed. The induction dryer typically does not need preheat time,does not give off hazardous gasses such as NOX, and allows for tightertemperature control. The tighter the temperature control, the less thelikelihood of gases evolving from the material being dried. Thus, thescrew auger drier may also be useful where environmental conditions needtight control, such as where an increase in gasses are objectionableand/or may complicate permitting issues.

However, the rotary drier may operate more efficiently. If time andspace are not critical, a rotary drier could be advantageous.

The sorting step preceding the mechanical drying may vary according tothe type of dryer, the material processed, i.e., the degree or type ofagglomeration or otherwise fused properties of the material, and/or thecontamination of the material. Contamination may occur, for example,where large pieces of scrap mix with the PCM because scrap and PCM areoften stored adjacent one another. Such scrap could damage a dryer orlimit further use of the PCM. In one embodiment using a rotary dryer,the sorting ahead of a rotary dryer may only need to be to a particlesize of 3″, or the sorting may be eliminated. However, an embodimentusing an auger may require screening, sorting, for example, to a maximumof about ¾ of an inch particle size or less. Other embodiments arecontemplated wherein no screening step is required due to the inherentsmall particle size and lack of contamination.

In some steel making processes, the PCM may remain dry throughoutgeneration and recovery. However, even without the moisture contentproblem, adding the PCM back into the steel making process may bedifficult. For example, injecting PCM may be difficult because of thelimited size of an injection gun compared to the size of some PCMparticles and other scrap metal which may tend to become mixed with thePCM. Also, injected PCM may displace slag foaming materials inhibitingnecessary chemical reaction between the steel and the slag.

Additional embodiments may include PCM that has not absorbed moistureand is below 2% moisture content in the drop box. Such “dry PCM” doesnot need to undergo a further drying process and may be screened and/ormixed with slag foaming materials for injection into the steel makingprocess, as will be discussed.

According to another embodiment of the current invention, the dried PCMcan be sorted further. This may include screening to give a size thatwill not block or clog an injection gun as is commonly used to add slagfoaming material in an electric arc furnace. This screening may be toabout 5/16 of an inch, i.e., to the size of the slag foaming material.Once the PCM has been sized to about 5/16 of an inch, it can proceed,for example, via a bucket elevator, into a first PCM container such as asilo. Once in a first container, the PCM can be discharged into a secondcontainer such as a super sack or a truck. The PCM can be mixedconcurrently with the slag foaming material to make a modified slagfoaming material. The modified slag foaming material can be added intothe top of an arc furnace, usually by an injection gun, to create afoamy slag on the top of the molten bath of steel.

In one embodiment of the current invention, the modified slag foamingmaterial is injected after slag has foamed on a heat of steel. Such anembodiment typically has an environment that is hot and oxygen richenough to cause the generally endothermic materials in the PCM to becomeexothermic, thus generating heat and reducing power usage. The oxygenmay create energy, for example, by oxidizing some of the iron in thePCM. The high temperature may also melt the iron from the PCM. Further,both the carbon from the slag foaming material and other metals in thePCM may reduce the oxidized iron, further allowing recovery of the ironinto the liquid steel. Such oxidation and reduction reactions are knownto those skilled in the art and may be reviewed by the Gibb's freeenergy equations and diagrams. An example of generating heat andreducing power will be discussed later.

A typical slag foaming material may consist of about 90% coal and about10% dolomitic stone. In one embodiment of the current invention, amodified slag foaming material, that is, a slag foaming material withPCM added, may comprise about 10 to 20% PCM, about 70 to 80% coal andabout 8 to 12% dolomitic stone. However, according to the principles ofthe current invention, a modified slag foaming material may comprisefrom about 0% up to about 30% by weight PCM, and behave efficiently inthe steel making process.

In additional embodiments, other slag foaming materials such as anyother carbon and/or low sulfur products, and/or materials includingcalcium and magnesium oxides, iron, carbon, and manganese, as known tothose skilled in the art, may be mixed with the PCM.

FIG. 1 illustrates one exemplary embodiment of a facility 30 for theprocessing of the PCM in accordance with the invention. The facility 30includes a first receiving hopper 40 for loading of PCM generated by thesteel making process. The material can be processed from the firstreceiving hopper 40 to a first screen 42. In one embodiment, the firstscreen 42 comprises a 5′ by 7′ double decked scalping screen. The firstscreen 42 screens the PCM to obtain a fraction having a desired maximumparticle size, for example, of about ¾ inch. The screened PCM fractionof the desired size is delivered via a discharge conveyer 44 to a firstscreen fraction or stockpile 46. Material too large to be screened bythe first screen 42 may be stockpiled, for example, in a screened“overs” stockpile 70, or otherwise processed to reduce its size, ordiscarded. Material from the first screened fraction stockpile 46 istransported, for example by a front end loader, a conveyor or the liketo a second receiving hopper 50. The PCM is next fed from the secondreceiving hopper 50 to screw auger 52. The auger 52 can be a heated,dewatering auger in certain embodiments. For example, the auger mayinclude induction heaters to heat the PCM and evaporate the watercontent of the material. In one embodiment, the PCM is heated to reducethe water content to less than about 2%. In other embodiments of thecurrent invention the auger 52 can be replaced by a conventional rotarydryer, or any other dryer effective to reduce the water content of thePCM.

Exiting the auger 52, the material is transported by a feed conveyor 54to a second screen 56. In one embodiment, the second screen 56 comprisesa 4′ by 8′ single deck scalping screen. The second screen 56 screens thePCM to obtain a fraction having a maximum particle size about ¼ inch.The screened PCM fraction is transported, for example, by a bucketelevator 58, to a first storage silo 60. In the embodiment of FIG. 1, asecond storage silo 62 is adjacent the storage silo 60. The secondstorage silo 62 may contain any of a variety of slag foaming materialssuch as anthracitic coal, coke, or any other carbon and/or any other lowsulfur product known to those skilled in the art for use in a steelmaking process. The slag foaming material may additionally includematerials such as dolomite or spar. Further, the two storage silos canhave a single load out spout (not shown). The single load out spout mayallow for mixing of the two materials concurrent with addition of thematerials to a container such as a transport truck.

Other sources of high iron-bearing steel waste material may be similarlyrecycled. Such materials include bag house dust, scale and iron fines.In alternative embodiments, driy high iron-bearing steel waste materialsmay be all be stored in a single silo, in combinations of silos, or eachin individual silos. In one embodiment of the current invention, the baghouse dust is stored in a storage silo similar to the PCM. The bag housedust is mixed directly with the slag foaming material. A single load outspout may also allow the mixing of the bag house dust with the slagfoaming material concurrently as the materials are added to a transporttruck. Since bag house dust typically has a moisture content that isless than 2%, a drying process is typically not necessary. Also, becausebag house dust is usually small in size, less than 5/16 inch, and istypically clean or free of other (larger) contaminants, it may not needto be sorted. However, should the bag house dust have a high moisturecontent greater than about 2%, or be agglomerated in particle size toolarge to inject, the drying and/or screening process, as described abovefor the PCM, may also be used.

Scale, as generated from steel processing, such as caster scale or millscale, may be treated similarly. However, since such scale may have ahigher concentration of iron oxide content, the concentration of scaleto slag foaming material may be adjusted. Also, scale is typically highin moisture content. High moisture content scale should be dried asdescribed above with respect to the PCM. That is, the scale may bedried, for example, by a rotary dryer or screw auger dryer to about 2%by weight or less water content. Further, the scale may be screenedbefore and after drying as needed to reach the previously discussedparticle sizes. Upon injection and between the scale contained in themodified slag foaming material and the high temperature slag shouldpossibly be exothermic because the Fe₃O₅ will be oxidized to Fe₂O₃.

Other iron-bearing materials, such as those generated by the steel coldfinishing processes, may also be mixed with slag foaming material toprovide a steel processing material. For example, the iron finesrecovered from cold mill rolling solution or temper mill rollingsolution or from cleaning processes, such as a cleaning process ingalvanizing line, may also be used. Again, these materials may be wet orof sufficiently large size that drying and/or screening may benecessary. Drying, screening, and/or mixing processes as discussed abovemay be employed. These materials are typical of high Fe content and maybehave similar to PCM in that the oxidation of the iron is an exothermicreaction. Also, a relatively high purity iron oxide may be recoveredfrom spent pickle liquor. This material, though possibly already driedby a roaster, may become wet or otherwise increase to moisture content.This material, too, may be screened, dried, and/or mixed according tothe methods previously discussed for use with the PCM. Depending on theparticular iron oxide materials available to cause an exothermicreaction with the high temperature slag.

An exempary comparison of batch recovered a charging PCM in chargebuckets, drying and mixing PCM with slag foaming materials will now bediscussed. Approximately 1,000 pounds of PCM is batch charged into a 200ton heat of steel. Nitrogen increases in the steel by 15 parts permillion (PPM). Further, when PCM is directly charged in the bucket, thekilowatt hour per scrap ton (KWH/ton) increases by about 37 KWH/ton.However, when the PCM is dried and mixed with slag foaming material inan amount of about 95% by weight slag foaming material and 5% by weightPCM, an increase in KWH is not seen and the KWH actually appears todecrease. This may be due to oxidation of iron and manganese. Also,there was no increased nitrogen in the steel and the FeO weight percentin the slag did not increase.

In this example, the dried and mixed PCM contains about 45% by weight ofiron and about 1.7% by weight of manganese. This equates to about 144pounds of iron and 5.4 pounds of manganese. One hundred forty-fourpounds of iron, when oxidized during the melting process fromapproximately 76° F. to 2,900° F. would create about 85 kilowatt hours,if reacted 100% to completion. However, at only 50% reaction, 43kilowatt hours would be produced. Similarly, 5.4 pounds of manganesereacted with oxygen from 76° F. to 2,900° F. generates about 5 KWH, whenreacted completely or 2.5 KWH when reacted 50%.

In the exemplary comparison, batch charging recovered PCM increases bothpower usage and the time necessary to melt a heat. These factors, alongwith possible decreased quality in steel, make recharging PCM directlyvery expensive, especially when considering that newly recovered PCM mayincrease power usage by approximately 8%. Alternatively, the dried andmixed PCM may decrease power usage by approximately 10%.

Additional embodiments of the current invention are directed to methodsof manufacturing steel. In one embodiment of this method, a first heatof steel is melted. A slag foaming material may also be added to theheat. A liquid steel portion and a foamy slag portion are developed. Themelting of the heat evolves both some of the steel and the foamy slag asfurnace exhaust materials. The furnace exhaust materials may beexhausted toward a bag house. Some of the materials (PCM) may be tooheavy or large or may be washed away from the exhaust by a water streamand may not be exhausted to the bag house. A drop out box is typicallyprovided to accumulate these materials.

In an embodiment of this method, the PCM may become wet from leaks,sprays, rain or any other source inside or external to the exhaust ductor to the drop out box. Thus, the PCM may need drying in accordance withthe methods discussed above. Drying may be achieved by a screw auger, arotary dryer, or the like. In other alternative embodiments, the PCM maynot be wet, but rather a moisture content less than about 2% by weight,and may proceed directly to further processing steps.

A method of sorting the PCM before drying, as previously discussed, maybe used to properly size the particles for the drying process. A methodof further sorting before storing, mixing, or injecting of the PCM maybe used as previously discussed.

Once dried and sorted as needed, the PCM is added into a second heat ofsteel. The PCM may be added by injection with an injection gun, mixingwith another material such as a slag foaming material and then injectedor added in batch.

As PCM undergoes the process of multiple iterations of being generated,recovered and added back into the steel making process, a build up inthe PCM of heavy metals such as zinc and lead may occur. In oneembodiment made in accordance with the current invention, a limit or setpoint, such as 0.0010% by weight of lead, is set for heavy metalconcentration in the PCM. Once the limit is met, the PCM is removed fromthe iterative process. For example, a clean steel producer may generatePCM that has heavy metals well below a threshold as set by regulation orthe producer. Each time PCM is added back into a heat and recoveredagain, the concentration of these heavy metals increases. As theconcentration of heavy metals in the PCM increases to the set point,typically less than the threshold, the PCM may be removed from theiterative process and sent to a reclamation process. The moreconcentrated heavy metals may offset the cost of reclamation, shouldimprove the efficiency of the reclamation process and may reduce thesteel makers need to land fill the PCM. However, in an additionalembodiment, the PCM with a high concentration of heavy metals may besent to a landfill. Similar embodiments may be maintained for bag housedust of any other iron bearing material.

Some of the beneficial characteristics of this invention may includeincreased liquid steel yield, decreased energy cost, decreased land fillrequirements, and decreased shipping and handling of waste material.Thus the invention both decreases cost for the steel industry andimproves the environment.

Having shown and described the preferred embodiments of the presentinvention, further adaptations to the post combustion material recyclingsystem of the present invention as described herein can be accomplishedby appropriate modifications by one of ordinary skill in the art withoutdeparting from the scope of the present invention. Several of thesepotential modifications and alternatives have been mentioned, and otherscan be apparent to those skilled in the art. For example, whileexemplary embodiments of the inventive system and process have beendiscussed for illustrative purposes, it should be understood that theelements described can be constantly updated and approved bytechnological advances. Similarly, as described, the process of thisinvention could be applied with any steel processing waste materialsubstantially bearing iron. Accordingly, the scope of the presentinvention should be considered in terms of the following claims and isunderstood not to be limited to the details of structure, operation orprocess steps as shown and described in this specification and drawing.

1-7. (canceled)
 8. A method of recycling exhaust waste material from anelectric arc furnace comprising: (a) recovering the exhaust wastematerial from an electric arc furnace; (b) drying the exhaust wastematerial; (c) adding scrap steel to the electric arc furnace; and (d)adding the exhaust waste material to the electric arc furnace whereiniron from the exhaust waste material is recycled.
 9. The method ofrecycling the exhaust waste material of claim 8 wherein drying isconducted in a screw auger dryer.
 10. The method of recycling theexhaust waste material of claim 9 wherein the screw auger dryercomprises an induction heater.
 11. The method of recycling the exhaustwaste material of claim 9 further comprising sorting the PCM to obtain afraction having an average particle size processable by the screw augerprior to drying.
 12. The method of recycling the exhaust waste materialof claim 11 wherein exhaust waste material is sorted to obtain afraction having a particle size of about ¾ of an inch.
 13. The method ofrecycling the exhaust waste material of claim 8 wherein the drying isconducted in a rotary dryer.
 14. The method of recycling the exhaustwaste material of claim 8 wherein drying the exhaust waste materialcomprises drying the exhaust waste material to not greater than about 2%water content.
 15. The method of recycling the exhaust waste material ofclaim 8 wherein drying the exhaust waste material comprises air dryingthe exhaust waste material to about 6% to about 8% water content. 16.The method of recycling the exhaust waste material of claim 8 furthercomprising sorting the exhaust waste material to obtain a fractionhaving an average particle size processable by an injection gun.
 17. Themethod of recycling the exhaust waste material of claim 16 wherein theexhaust waste material is sorted to obtain a fraction having a maximumparticle size of about 5/16 of an inch.
 18. The method of recycling theexhaust waste material of claim 8 further comprising conveying the driedexhaust waste material to a first container.
 19. The method of recyclingthe exhaust waste material of claim 8 further comprising mixing thedried exhaust waste material with a slag foaming material.
 20. Themethod of recycling the exhaust waste material of claim 19 whereinmixing is conducted by adding the dried exhaust waste material andconcurrently adding slag foaming material into a container.
 21. A methodof preparing a steel processing material comprising: (a) recovering drypost combustion material (PCM) from a steel making process; and (b)mixing the PCM with a slag foaming material.
 22. A method ofmanufacturing steel in an electric arc furnace comprising: (a) meltingin the electric arc furnace a first heat of steel comprising a liquidsteel portion and a foamy slag portion; (b) evacuating the emissionsfrom the first ehat wherein solid waste material is exhausted from theheat; mixing the solid waste material with a slag foaming material toform a steel processing material; and (d) adding the steel processingmaterial into a second heat of steel.
 23. The method of manufacturingsteel of claim 22 wherein the solid waste material is recovered from thefirst heat.
 24. The method of manufacturing steel of claim 22 furthercomprising drying the solid waste material before mixing the solid wastematerial with a slag foaming material.
 25. The method of manufacturingsteel of claim 22 wherein the adding of the steel processing materialinto a second heat of steel comprises injecting the steel processingmaterial with an injection gun. 26-27. (canceled)
 28. The method ofmanufacturing steel of claim 23 wherein the steps of melting, drying andadding are repeated until the concentration of heavy metals in the PCMreaches a set point.
 29. The method of manufacturing steel of claim 28further comprising sending the PCM to a reclamation process once theconcentration of heavy metals in the PCM reaches the set point.
 30. Themethod of manufacturing steel of claim 22 wherein the steps are repeateduntil the concentration of heavy metals in the solid waste materialreaches a set point.
 31. The method of manufacturing steel of claim 30further comprising sending the PCM to a reclamation process once theconcentration of heavy metals in the PCM reaches the set point.